A "full battle group" of 1,350 personnel is to be sent to Poland for a Nato exercise to reassure Eastern European allies in the face of Russia's conflict with Ukraine.

Defence Secretary Michael Fallon confirmed the deployment and said more than 350 armoured and other vehicles would take part.

Exercise Black Eagle will be held in October and is part of a series of Nato exercises designed to support allies in Eastern Europe and the Baltics.

Next month, light infantry troops from 1st Battalion, The Duke of Lancaster's Regiment will also join Exercise Sabre Junction, a US-led exercise - again taking place in Poland - and involving 16 countries.

Four RAF Eurofighter Typhoon jets have been at Nato's Baltic Air Policing mission, based at Lithuania's Siauliai Air Base, since Russia annexed the Crimean region of Ukraine earlier this year.

Normally the mission involves just four aircraft, but since the crisis in Ukraine it has been boosted to 12, including four Lockheed Martin F-16 jets from Denmark and four MiG-29 planes from Poland.

Mr Fallon announced details of the latest exercise during a visit to the Polish capital Warsaw with Foreign Secretary Philip Hammond.

Image:Michael Fallon was recently appointed as Defence Secretary

He said: "It is right that Nato members and partners demonstrate our commitment to the collective security of our allies in Eastern Europe, so I am pleased to confirm our participation in these exercises.

"In particular, the commitment of a battle group to Exercise Black Eagle shows our sustained and substantial support to Nato's eastern border."

A Nato summit in Wales in September is also being held to discuss ways to respond to future threats and reassurance measures.